Support creating and using multichain API sessions

Author: FrederikBolding

packages/examples/packages/multichain-provider/snap.manifest.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/MetaMask/snaps.git"
   },
   "source": {
-    "shasum": "CJiAtl5nGAZkZbPg4iyLxboK9t1qFs2glulvFYQoW8c=",
+    "shasum": "h+Tn09Nkej5V97sNnoVXIBlZ+qCoRHQcvUVwwtIbGTU=",
     "location": {
       "npm": {
         "filePath": "dist/bundle.js",

packages/examples/packages/multichain-provider/src/index.test.ts

@@ -20,6 +20,31 @@ describe('onRpcRequest', () => {
     });
   });
 
+  describe('createSession', () => {
+    it('returns the established session', async () => {
+      const { request } = await installSnap();
+
+      const response = await request({
+        method: 'createSession',
+      });
+
+      expect(response).toRespondWith({
+        sessionScopes: {
+          'eip155:1': {
+            accounts: [],
+            methods: expect.any(Array),
+            notifications: expect.any(Array),
+          },
+          'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp': {
+            accounts: [],
+            methods: expect.any(Array),
+            notifications: expect.any(Array),
+          },
+        },
+      });
+    });
+  });
+
   describe('getChainId', () => {
     const MOCK_CHAIN_ID = '0x01'; // Ethereum Mainnet
 
@@ -38,6 +63,8 @@ describe('onRpcRequest', () => {
     it('returns the addresses granted access to by the user', async () => {
       const { request } = await installSnap();
 
+      await request({ method: 'createSession' });
+
       const response = await request({
         method: 'getAccounts',
       });
@@ -53,9 +80,11 @@ describe('onRpcRequest', () => {
     const MOCK_SIGNATURE =
       '0x16f672a12220dc4d9e27671ef580cfc1397a9a4d5ee19eadea46c0f350b2f72a4922be7c1f16ed9b03ef1d3351eac469e33accf5a36194b1d88923701c2b163f1b';
 
-    it('returns a signature', async () => {
+    it('returns a signature for Ethereum', async () => {
       const { request, mockJsonRpc } = await installSnap();
 
+      await request({ method: 'createSession' });
+
       // We can mock the signature request with the response we want.
       mockJsonRpc({
         method: 'personal_sign',
@@ -64,7 +93,7 @@ describe('onRpcRequest', () => {
 
       const response = await request({
         method: 'signMessage',
-        params: { message: 'foo' },
+        params: { scope: 'eip155:1', message: 'foo' },
       });
 
       expect(response).toRespondWith(MOCK_SIGNATURE);
@@ -75,9 +104,11 @@ describe('onRpcRequest', () => {
     const MOCK_SIGNATURE =
       '0x01b37713300d99fecf0274bcb0dfb586a23d56c4bf2ed700c5ecf4ada7a2a14825e7b1212b1cc49c9440c375337561f2b7a6e639ba25be6a6f5a16f60e6931d31c';
 
-    it('returns a signature', async () => {
+    it('returns a signature for Ethereum', async () => {
       const { request, mockJsonRpc } = await installSnap();
 
+      await request({ method: 'createSession' });
+
       // We can mock the signature request with the response we want.
       mockJsonRpc({
         method: 'eth_signTypedData_v4',
@@ -86,10 +117,27 @@ describe('onRpcRequest', () => {
 
       const response = await request({
         method: 'signTypedData',
-        params: { message: 'foo' },
+        params: { scope: 'eip155:1', message: 'foo' },
       });
 
       expect(response).toRespondWith(MOCK_SIGNATURE);
     });
   });
+
+  describe('getGenesisHash', () => {
+    it('returns a hash', async () => {
+      const { request } = await installSnap();
+
+      await request({ method: 'createSession' });
+
+      const response = await request({
+        method: 'getGenesisHash',
+        params: { scope: 'eip155:1' },
+      });
+
+      expect(response).toRespondWith(
+        '0xd4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3',
+      );
+    });
+  });
 });

packages/examples/packages/multichain-provider/src/index.ts

@@ -119,6 +119,9 @@ export const onRpcRequest: OnRpcRequestHandler = async ({ request }) => {
       return await scopeModule.signMessage(accounts[0], params.message);
     }
 
+    case 'getGenesisHash':
+      return await scopeModule.getGenesisHash();
+
     default:
       throw new MethodNotFoundError({ method: request.method });
   }

packages/snaps-simulation/package.json

@@ -55,6 +55,7 @@
     "test:watch": "jest --watch"
   },
   "dependencies": {
+    "@metamask/chain-agnostic-permission": "^1.4.0",
     "@metamask/json-rpc-engine": "^10.1.0",
     "@metamask/json-rpc-middleware-stream": "^8.0.8",
     "@metamask/key-tree": "^10.1.1",

packages/snaps-simulation/src/controllers.ts

@@ -1,3 +1,7 @@
+import {
+  caip25CaveatBuilder,
+  Caip25CaveatType,
+} from '@metamask/chain-agnostic-permission';
 import { Messenger } from '@metamask/messenger';
 import type {
   CaveatSpecificationConstraint,
@@ -145,6 +149,11 @@ function getPermissionController(options: GetControllersOptions) {
   return new PermissionController({
     messenger,
     caveatSpecifications: {
+      // @ts-expect-error Missing args temporarily.
+      [Caip25CaveatType]: caip25CaveatBuilder({
+        findNetworkClientIdByChainId: (chainId) => chainId,
+        isNonEvmScopeSupported: (_scope) => true,
+      }),
       ...snapsCaveatsSpecifications,
       ...snapsEndowmentCaveatSpecifications,
     },

packages/snaps-simulation/src/methods/specifications.ts

@@ -1,3 +1,4 @@
+import { caip25EndowmentBuilder } from '@metamask/chain-agnostic-permission';
 import type { GenericPermissionController } from '@metamask/permission-controller';
 import {
   endowmentPermissionBuilders,
@@ -81,6 +82,8 @@ export function getPermissionSpecifications({
   options,
 }: GetPermissionSpecificationsOptions) {
   return {
+    [caip25EndowmentBuilder.targetName]:
+      caip25EndowmentBuilder.specificationBuilder({}),
     ...buildSnapEndowmentSpecifications(EXCLUDED_SNAP_ENDOWMENTS),
     ...buildSnapRestrictedMethodSpecifications(EXCLUDED_SNAP_PERMISSIONS, {
       // Shared hooks.

packages/snaps-simulation/src/middleware/internal-methods/middleware.ts

@@ -4,7 +4,11 @@ import type { Hex, Json, JsonRpcParams } from '@metamask/utils';
 
 import { getAccountsHandler } from './accounts';
 import { getChainIdHandler } from './chain-id';
-import { getSessionHandler } from './multichain';
+import {
+  createSessionHandler,
+  getSessionHandler,
+  invokeMethodHandler,
+} from './multichain';
 import { getNetworkVersionHandler } from './net-version';
 import { getSwitchEthereumChainHandler } from './switch-ethereum-chain';
 import type { ApplicationState } from '../../store';
@@ -39,7 +43,9 @@ const methodHandlers = {
   eth_chainId: getChainIdHandler,
   net_version: getNetworkVersionHandler,
   wallet_switchEthereumChain: getSwitchEthereumChainHandler,
+  wallet_createSession: createSessionHandler,
   wallet_getSession: getSessionHandler,
+  wallet_invokeMethod: invokeMethodHandler,
   /* eslint-enable @typescript-eslint/naming-convention */
 };
 

packages/snaps-simulation/src/middleware/internal-methods/multichain/create-session.ts

@@ -0,0 +1,68 @@
+import { getSessionScopes } from '@metamask/chain-agnostic-permission';
+import type {
+  JsonRpcEngineEndCallback,
+  JsonRpcEngineNextCallback,
+} from '@metamask/json-rpc-engine';
+import type { RequestedPermissions } from '@metamask/permission-controller';
+import { rpcErrors } from '@metamask/rpc-errors';
+import {
+  isObject,
+  type JsonRpcRequest,
+  type PendingJsonRpcResponse,
+} from '@metamask/utils';
+
+export type CreateSessionHandlerHooks = {
+  grantPermissions: (permissions: RequestedPermissions) => void;
+};
+
+/**
+ * A handler that implements a simplified version of `wallet_createSession`.
+ *
+ * @param request - Incoming JSON-RPC request.
+ * @param response - The outgoing JSON-RPC response, modified to return the
+ * result.
+ * @param _next - The `json-rpc-engine` middleware next handler.
+ * @param end - The `json-rpc-engine` middleware end handler.
+ * @param hooks - The method hooks.
+ * @returns The JSON-RPC response.
+ */
+export async function createSessionHandler(
+  request: JsonRpcRequest,
+  response: PendingJsonRpcResponse,
+  _next: JsonRpcEngineNextCallback,
+  end: JsonRpcEngineEndCallback,
+  hooks: CreateSessionHandlerHooks,
+) {
+  if (!isObject(request.params)) {
+    return end(rpcErrors.invalidParams({ data: { request } }));
+  }
+
+  const caveat = {
+    requiredScopes: request.params.requiredScopes ?? {},
+    optionalScopes: request.params.optionalScopes ?? {},
+    sessionProperties: {},
+    isMultichainOrigin: true,
+  };
+
+  const permissions = {
+    'endowment:caip25': {
+      caveats: [
+        {
+          type: 'authorizedScopes',
+          value: caveat,
+        },
+      ],
+    },
+  };
+
+  // @ts-expect-error Ignore for now.
+  hooks.grantPermissions(permissions);
+
+  // @ts-expect-error Ignore for now.
+  const sessionScopes = getSessionScopes(caveat, {
+    getNonEvmSupportedMethods: () => [],
+  });
+
+  response.result = { sessionScopes };
+  return end();
+}

packages/snaps-simulation/src/middleware/internal-methods/multichain/get-session.ts

@@ -1,3 +1,7 @@
+import {
+  Caip25CaveatType,
+  Caip25EndowmentPermissionName,
+} from '@metamask/chain-agnostic-permission';
 import type {
   JsonRpcEngineEndCallback,
   JsonRpcEngineNextCallback,
@@ -14,7 +18,7 @@ export type GetSessionHandlerHooks = {
 };
 
 /**
- * A handler that implements `wallet_getSession`.
+ * A handler that implements a simplified version of `wallet_getSession`.
  *
  * @param _request - Incoming JSON-RPC request. Ignored for this specific
  * handler.
@@ -32,6 +36,14 @@ export async function getSessionHandler(
   end: JsonRpcEngineEndCallback,
   hooks: GetSessionHandlerHooks,
 ) {
-  response.result = hooks.getCaveat('endowment:caip25', 'authorizedScopes');
+  try {
+    const caveat = hooks.getCaveat(
+      Caip25EndowmentPermissionName,
+      Caip25CaveatType,
+    );
+    response.result = { sessionScopes: caveat?.value ?? {} };
+  } catch {
+    response.result = { sessionScopes: {} };
+  }
   return end();
 }

packages/snaps-simulation/src/middleware/internal-methods/multichain/index.ts

@@ -1 +1,3 @@
+export * from './create-session';
 export * from './get-session';
+export * from './invoke-method';